For our analysis, we have taken only those seats which have got their bets right for the past five Lok Sabha elections.

Bellwether seats are ones which determine who forms government at Centre | AP photo for representation

While everyone in the country is curious to know who will reach, or even cross, the 272 majority number on May 23, the answer could lie in how the people in 20 constituencies vote. India Today's Data Intelligence Unit (DIU) has found that these seats may likely decide the fate of who will win the elections, if they continue to follow the pattern that they have set over the past five elections.

Since the 1998 Lok Sabha elections, these 20 constituencies have always elected a party or an alliance that has later gone on to form the government at the Centre. This is why they're often referred to as 'bellwether seats'.

For our analysis, we have taken only those seats which have got their bets right for the past five Lok Sabha elections.

Of these 20 bellwether seats, Andhra Pradesh, Delhi, Gujarat and Haryana have three each while Jharkhand has two.

Four of the 20 seats are reserved constituencies - Valsad (ST) from Gujarat, Sasaram(SC) from Bihar, Palamau (SC) from Jharkhand and Amalapuram (SC) from Andhra Pradesh.

WHICH ARE THESE 20 SEATS?

(Click image to enlarge)

For simplicity, we have divided our analysis to focus separately on the four regions of the country.

NORTH INDIA: DELHI, HARYANA, J&K, AND HIMACHAL PRADESH

Delhi has three bellwether seats - East Delhi, New Delhi and Chandni Chowk.

Congress party's Kapil Sibal will be contesting from Chandni Chowk this time again. Sibal won the seat in 2004 and 2009, but in 2014, he finished at the third place after losing to Harsh Vardhan of the BJP and Ashutosh of AAP (first runner-up).

For the East Delhi seat currently presided by BJP's Maheish Girri, AAP is fielding its popular leader leader Atishi.

The three bellwether seats in Haryana are Bhiwani-Mahendragarh, Faridabad, and Kurukshetra. Congress's recent loss in the Jind bypoll and weak leadership is echoing in other areas in the state. The party is struggling to field candidates in Haryana and state leaders do not seem to be very enthusiastic too.

Himachal Pradesh's Mandi has witnessed single-digit margins of victory since 2004, making the fight tougher between the BJP and Congress. In 2014, BJP's Ram Swaroop Sharma had defeated six-time MP Pratibha Singh, wife of former CM Virbhadra Singh. Swaroop has jumped into the fray again but this time his opponent from the Congress is Ashray Sharma, grandson of Sukh Ram, former Union minister and three-time MP from Mandi.

Jammu constituency also finds a place in the list. Jugal Kishore Sharma of BJP had won from here in 2014 and is contesting again while the Congress is fielding former minister Raman Bhalla. The BJP had sought for disqualification against Bhalla over the alleged communal remarks made by his wife.

Bellwether seats: North India. (Click to enlarge)

Bellwether Seats: North India

WEST INDIA: GUJARAT AND MAHARASHTRA

Gujarat is home to three bellwether seats - Banaskantha, Valsad and Jamnagar.

Valsad, a seat reserved for Scheduled Tribes, has the unique distinction of having voted for the party that formed the government at the Centre in all the past Lok Sabha elections held till date.

In 2017, a Delhi woman had put rape allegations on the BJP MP from Valsad, KC Patel, which he denied by calling it a case of 'honey trapping'.

Standing against Patel is Congress party's Jitubhai Chaudhari, a four-time MLA of the Kaprada (ST). This time, the battle could be interesting as Chaudhari is a stronger and more popular face than Patel in the constituency.

Maharashtra finds only one seat in our analysis, Mumbai North. Like the city, this seat too has glamour attached to it. The seat was won by actor-turned-politician Govinda in 2004, on a Congress ticket. This time another actor, Urmila Matondkar, is contesting the seat, again as a Congress member, while the BJP is fielding the its 2014 candidate, Gopal Chinayya Shetty.

Bellwether seats: Western India (Click to enlarge)

SOUTH INDIA: ANDHRA PRADESH, TELANGANA AND TAMIL NADU

Amalapuram (SC), Kakinada and Rajahmundry of Andhra Pradesh, Secunderabad in Telangana, and Dharmapuri in Tamil Nadu have made it to our bellwether list from South India.

Of these, Dharmapuri has shown a peculiar trend. In the past five elections, this constituency has elected the regional party Pattali Makkal Katchi (PMK) four times though the party had different alliances each time.

In 1998 and 1999 elections, the PMK supported NDA and won the seat, but in 2004 the party supported the UPA, and won again. In 2009, the Dharmapuri seat went to the DMK which was an ally to the UPA 2. But in 2014, the PMK managed to bounce back to the winner's position though it had switched allegiance to the BJP. This year too, the PMK has joined with the NDA and is fielding its 2014 winner, Anbumani Ramadoss.

Bellwether seats: South India (Click to enlarge)

EAST INDIA: BIHAR AND JHARKHAND

Two seats from Jharkhand have made it to our list - Ranchi and Palamau.

Since 1998, Ranchi has seen tough competition between two candidates, Subodh Kant Sahay of Congress and Ram Tahal Choudhary, a five-time BJP MP from the constituency who has decided to contest as an independent candidate this time, after being denied a ticket by the BJP.

This will make Ranchi a triangular fight between five-time MP Choudhary, three-time MP Sahay and the BJP candidate, Sanjay Seth.

Sasaram, a constituency reserved for the Scheduled Castes, was won by Chhedi Paswan of the BJP in 2014. The seat was presided two times by former union minister Meira Kumar, who was the speaker of the Lok Sabha during the UPA 2. This time too, the duel will be between Meira and Paswan.

Bellwether seats: Eastern India (Click to enlarge)

DO THESE FIGURES REALLY MATTER?

While these figures might have fascinated the media, psephologists believe that in India, the phenomenon of bellwether seats is a mere coincidence.

According to psephologist Yashwant Deshmukh, the complexity of Indian governance system makes it difficult to tag a seat as a perfect bellwether seat.

"India has three layers of government - Centre, state and local body. Each election has different anger points and incumbencies, and all these elections happen at different times. So, it will be rare to see bellwether behaviour at all levels at a given point of time making it extremely difficult to predict anything. It might amuse, but it is a mere correlation," Yashwant Deshmukh said.

Journalist Prannoy Roy in his book says, "It would be highly unlikely for demographic change in one area to closely mirror demographic change of the whole state or nation. What might be the perfect bellwether in one election could grow significantly out of sync with the nation by the next".

Sanjay Kumar, professor and director at the Centre for the Study of Developing Societies, says that bellwether seats are not a result of any correlation.

"In my opinion, bellwether seats aren't coming because of correlation. It is just coincidence that they elect the party/alliance that forms the government at the centre. Election will be won by the party that will win 272 seats, bellwether seats appearing in them would be just chance," Sanjay Kumar said.